Image-Based Visual-Impedance Control of a Dual-Arm Aerial Manipulator

Three new image-based visual-impedance control laws are proposed in this paper allowing physical interaction of a dual-arm unmanned aerial manipulator equipped with a camera and a force/torque sensor. Namely, two first-order impedance behaviours are designed based on the transpose and the inverse of the system Jacobian matrix, respectively, while a second-order impedance behaviour is carried out as well. Visual information is employed both to coordinate the camera motion in an eye- in-hand configuration with the assigned task executed by the other robot arm, and to define the elastic wrench component of the proposed hybrid impedance equations directly in the image plane

6D physical interaction with a fully actuated aerial robot

This paper presents the design, control, and experimental validation of a novel fully-actuated aerial robot for physically interactive tasks, named Tilt-Hex. We show how the Tilt-Hex, a tilted-propeller hexarotor is able to control the full pose (position and orientation independently) using a geometric control, and to exert a full-wrench (force and torque independently) with a rigidly attached end-effector using an admittance control paradigm. An outer loop control governs the desired admittance behavior and an inner loop based on geometric control ensures pose tracking. The interaction forces are estimated by a momentum based observer. Control and observation are made possible by a precise control and measurement of the speed of each propeller. An extensive experimental campaign shows that the Tilt-Hex is able to outperform the classical underactuated multi-rotors in terms of stability, accuracy and dexterity and represent one of the best choice at date for tasks requiring aerial physical interaction

Arbitrary Convergence Time Control for Aerial Manipulator with TSK Estimator

This paper investigates the stable control problem of unmanned aerial manipulator (UAM) in the presence of lumped disturbance, including modelling uncertainties and external inferences. These disturbances typically involve limited prior knowledge and change rapidly, presenting considerable challenges to real-time control accuracy. To address this issue, a Takagi-Sugeno-Kang estimator (TSKE) with K-closest fuzzy rules interpolation (K-FRI) is proposed to derive an approximation for the uncertain disturbances. The incorporation of K-FRI enhances the accuracy and convergence rate of the estimation under the conditions of a sparse fuzzy rule base with an incomplete fuzzy quantity space. Subsequently, a backstepping controller with arbitrary convergence time is introduced to guarantee the rapid and precise control of the UAM. The stability of both the TSKE and the controller with arbitrary convergence time is analysed through Lyapunov theory. The feasibility and performance of the proposed control strategy are validated via comparative experimental simulations, demonstrating its ability for robust estimation capability with stable control performance, at any convergence time of the UAM working under lumped disturbance

Arbitrary Convergence Time Control for Aerial Manipulator with TSK Estimator

This paper investigates the stable control problem of unmanned aerial manipulator (UAM) in the presence of lumped disturbance, including modelling uncertainties and external inferences. These disturbances typically involve limited prior knowledge and change rapidly, presenting considerable challenges to real-time control accuracy. To address this issue, a Takagi-Sugeno-Kang estimator (TSKE) with K-closest fuzzy rules interpolation (K-FRI) is proposed to derive an approximation for the uncertain disturbances. The incorporation of K-FRI enhances the accuracy and convergence rate of the estimation under the conditions of a sparse fuzzy rule base with an incomplete fuzzy quantity space. Subsequently, a backstepping controller with arbitrary convergence time is introduced to guarantee the rapid and precise control of the UAM. The stability of both the TSKE and the controller with arbitrary convergence time is analysed through Lyapunov theory. The feasibility and performance of the proposed control strategy are validated via comparative experimental simulations, demonstrating its ability for robust estimation capability with stable control performance, at any convergence time of the UAM working under lumped disturbance

An aerial parallel manipulator with shared compliance

Accessing and interacting with difficult to reach surfaces at various orientations is of interest within a variety of industrial contexts. Thus far, the predominant robotic solution to such a problem has been to leverage the maneuverability of a fully actuated, omnidirectional aerial manipulator. Such an approach, however, requires a specialised system with a high relative degree of complexity, thus reducing platform endurance and real-world applicability. The work here presents a new aerial system composed of a parallel manipulator and conventional, underactuated multirotor flying base to demonstrate interaction with vertical and non-vertical surfaces. Our solution enables compliance to external disturbance on both subsystems, the manipulator and flying base, independently with a goal of improved overall system performance when interacting with surfaces. To achieve this behaviour, an admittance control strategy is implemented on various layers of the flying base's dynamics together with torque limits imposed on the manipulator actuators. Experimental evaluations show that the proposed system is compliant to external perturbations while allowing for differing interaction behaviours as compliance parameters of each subsystem are altered. Such capabilities enable an adjustable form of dexterity in completing sensor installation, inspection and aerial physical interaction tasks. A video of our system interacting with various surfaces can be found here: https://youtu.be/38neGb8-lXg

Aerial Manipulation: A Literature Review

Aerial manipulation aims at combining the versatil- ity and the agility of some aerial platforms with the manipulation capabilities of robotic arms. This letter tries to collect the results reached by the research community so far within the field of aerial manipulation, especially from the technological and control point of view. A brief literature review of general aerial robotics and space manipulation is carried out as well

Equilibrium-Based Force and Torque Control for an Aerial Manipulator to Interact with a Vertical Surface

In this paper, a force and torque controller for aerial manipulation is developed using an unmanned aerial vehicle equipped with a robotic arm to interact near or on a vertical surface such as a wall. Control of aerial manipulators interacting with the environment is a challenging task due to dynamic interactions between aerial vehicles, robotic arms, and environment. To achieve this, modeling of aerial manipulators is first investigated and presented considering interaction with the environment. Nonlinear models of generic aerial manipulators, as well as of a prototype aerial manipulator composed of a hexacopter with a three-joint robotic arm, are established. An equilibrium-based force and torque controller is developed to conduct tasks that require the aerial manipulator to exert forces and torques on a wall. Simulations and experiments validate the performance of the controller that successfully applies desired forces and torques to an object fixed on a wall while flying near the wall